3080 vs 3080ti may not have significant speed difference worthy of upgrading, but it is the vram (8gb to 16gb....10gb to 20gb) that will make those 3080, 3070 buyers upgrade hehe.
I guess if that comes to happen, it will be like the 1080 x 1080ti, performance like or a bit lower than 3900 but cheaper and 384bit + 20gb, 3080ti around $1199, I guess.
memory bus for both 3080 and 3080ti is both 320 bit. that's why speed improvement might be mininmal, 20gb however is a must for upcoming games textures at 4k